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Project No. D-3885-06 <br />Chrisl Our Savior Catholic Parish <br />For cantilevered walls, an active earth pressure of 40 pcf/ft and for restrained walls <br />(depressed sections, elevator shaft, etc.), an at-rest earth pressure of 60 pcf/ft should be <br />used. Passive earth pressure of 250 pounds per square foot per foot of depth, to a <br />maximum value of3,000 pounds per square foot may be used to detennine lateral bearing <br />resistance for footings. A coefficient of friction of 0.40 times the dead load may be used <br />between concrete and the supporting soils to determine lateral sliding resistance for the <br />building footings. The above lateral resistance values are based on footings placed <br />directly against compacted fill. <br />Any subterranean building walls including elevator shafts should be water proofed on the <br />outside face, considering the relatively high groundwater levels at the site. It is also <br />recommended that positive means be provided for accumulating subsurface percolation <br />and directing any water around the subterranean building perimeter away from the <br />building. <br />A pipe and gravel drain (4" perforated PVC embedded in at least three cubic feet of filter <br />gravel per lineal foot of pipe, both wrapped with l40N or equivalent geofabric) should be <br />provided on the retained side of any subterranean building areas. This should be located <br />near the top of the footing base on the outside face. While all backfill should be <br />compacted to the required degree, care should be taken when working close to walls to <br />prevent excessive pressure. <br />Corrosion and Sulfate Attack Protection <br />A major factor in detennining soil corrosivity is electrical Resistivity. The electrical <br />Resistivity of a soil is a measure of its resistance to the flow of electrical current. <br />Corrosion of buried metal is an electrochemical process in which the amount of metal loss <br />due to corrosion is directly proportional to the flow of electrical current (DC) from the <br />metal into the soil. Corrosion currents, following Ohm's Law, are inversely proportional <br />to soil Resistivity. Lower electrical resistivities result from higher moisture and chemical <br />lt <br />I <br />I <br />I <br />: <br />I <br />t <br />I <br />2 <br />t <br />I <br />I <br />t <br />I <br />t <br />I <br />I <br />f <br />I 35